// Copyright (c) 2012-2025 fo-dicom contributors.
// Licensed under the Microsoft Public License (MS-PL).

// ReSharper disable CheckNamespace

// Note: these attributes exist in .NET Standard 2.1 or .NET Core 3.1 and up
// If we ever move away from .NET Standard 2.0, this whole file can be removed
// Until then, we can benefit from nullability analysis by copying these attributes inline
namespace System.Diagnostics.CodeAnalysis
{
    /// <summary>
    /// Specifies that null is allowed as an input even if the corresponding type disallows it.
    /// </summary>
    [AttributeUsage(
        AttributeTargets.Field |
        AttributeTargets.Parameter |
        AttributeTargets.Property,
        Inherited = false)]
    [ExcludeFromCodeCoverage]
    internal sealed class AllowNullAttribute : Attribute
    {
    }
    
    /// <summary>
    /// Specifies that null is disallowed as an input even if the corresponding type allows it.
    /// </summary>
    [AttributeUsage(
        AttributeTargets.Field |
        AttributeTargets.Parameter |
        AttributeTargets.Property,
        Inherited = false)]
    [ExcludeFromCodeCoverage]
    internal sealed class DisallowNullAttribute : Attribute
    {
    }
    
    /// <summary>
    /// Applied to a method that will never return under any circumstance.
    /// </summary>
    [AttributeUsage(AttributeTargets.Method, Inherited = false)]
    [ExcludeFromCodeCoverage]
    internal sealed class DoesNotReturnAttribute : Attribute
    {
    }
    
    /// <summary>
    /// Specifies that the method will not return if the associated Boolean parameter is passed the specified value.
    /// </summary>
    [AttributeUsage(AttributeTargets.Parameter, Inherited = false)]
    [ExcludeFromCodeCoverage]
    internal sealed class DoesNotReturnIfAttribute : Attribute
    {
        /// <summary>
        /// Initializes the attribute with the specified parameter value.
        /// </summary>
        /// <param name="parameterValue">
        /// The condition parameter value. Code after the method will be considered unreachable
        /// by diagnostics if the argument to the associated parameter matches this value.
        /// </param>
        public DoesNotReturnIfAttribute(bool parameterValue) => ParameterValue = parameterValue;

        /// <summary>
        /// Gets the condition parameter value.
        /// </summary>
        public bool ParameterValue { get; }
    }
    
    /// <summary>
    /// Specifies that an output may be null even if the corresponding type disallows it.
    /// </summary>
    [AttributeUsage(
        AttributeTargets.Field |
        AttributeTargets.Parameter |
        AttributeTargets.Property |
        AttributeTargets.ReturnValue,
        Inherited = false)]
    [ExcludeFromCodeCoverage]
    internal sealed class MaybeNullAttribute : Attribute
    {
    }
    
    /// <summary>
    /// Specifies that when a method returns <see cref="ReturnValue"/>, the parameter may be null even if the corresponding type disallows it.
    /// </summary>
    [AttributeUsage(AttributeTargets.Parameter, Inherited = false)]
    [ExcludeFromCodeCoverage]
    internal sealed class MaybeNullWhenAttribute : Attribute
    {
        /// <summary>
        /// Initializes the attribute with the specified return value condition.
        /// </summary>
        /// <param name="returnValue">The return value condition. If the method returns this value, the associated parameter may be null.</param>
        public MaybeNullWhenAttribute(bool returnValue) => ReturnValue = returnValue;

        /// <summary>
        /// Gets the return value condition.
        /// </summary>
        public bool ReturnValue { get; }
    }
    
    /// <summary>
    /// Specifies that the method or property will ensure that the listed field and property members have not-null values.
    /// </summary>
    [AttributeUsage(
        AttributeTargets.Method |
        AttributeTargets.Property,
        Inherited = false, AllowMultiple = true)]
    [ExcludeFromCodeCoverage]
    internal sealed class MemberNotNullAttribute : Attribute
    {
        /// <summary>
        /// Initializes the attribute with a field or property member.
        /// </summary>
        /// <param name="member">The field or property member that is promised to be not-null.</param>
        public MemberNotNullAttribute(string member) => Members = new[] { member };

        /// <summary>
        /// Initializes the attribute with the list of field and property members.
        /// </summary>
        /// <param name="members">The list of field and property members that are promised to be not-null.</param>
        public MemberNotNullAttribute(params string[] members) => Members = members;

        /// <summary>
        /// Gets field or property member names.
        /// </summary>
        public string[] Members { get; }
    }
    
        /// <summary>
    /// Specifies that the method or property will ensure that the listed field and property
    /// members have not-null values when returning with the specified return value condition.
    /// </summary>
    [AttributeUsage(
        AttributeTargets.Method |
        AttributeTargets.Property,
        Inherited = false, AllowMultiple = true)]
    [ExcludeFromCodeCoverage]
    internal sealed class MemberNotNullWhenAttribute : Attribute
    {
        /// <summary>
        /// Initializes the attribute with the specified return value condition and a field or property member.
        /// </summary>
        /// <param name="returnValue">The return value condition. If the method returns this value, the associated parameter will not be null.</param>
        /// <param name="member">The field or property member that is promised to be not-null.</param>
        public MemberNotNullWhenAttribute(bool returnValue, string member)
        {
            ReturnValue = returnValue;
            Members = new[] { member };
        }

        /// <summary>
        /// Initializes the attribute with the specified return value condition and list of field and property members.
        /// </summary>
        /// <param name="returnValue">The return value condition. If the method returns this value, the associated parameter will not be null.</param>
        /// <param name="members">The list of field and property members that are promised to be not-null.</param>
        public MemberNotNullWhenAttribute(bool returnValue, params string[] members)
        {
            ReturnValue = returnValue;
            Members = members;
        }

        /// <summary>
        /// Gets the return value condition.
        /// </summary>
        public bool ReturnValue { get; }

        /// <summary>
        /// Gets field or property member names.
        /// </summary>
        public string[] Members { get; }
    }
        
    /// <summary>
    /// Specifies that an output will not be null even if the corresponding type allows it.
    /// Specifies that an input argument was not null when the call returns.
    /// </summary>
    [AttributeUsage(
        AttributeTargets.Field |
        AttributeTargets.Parameter |
        AttributeTargets.Property |
        AttributeTargets.ReturnValue,
        Inherited = false)]
    [ExcludeFromCodeCoverage]
    internal sealed class NotNullAttribute : Attribute
    {
    }
    
    /// <summary>
    /// Specifies that the output will be non-null if the named parameter is non-null.
    /// </summary>
    [AttributeUsage(
        AttributeTargets.Parameter |
        AttributeTargets.Property |
        AttributeTargets.ReturnValue,
        AllowMultiple = true, Inherited = false)]
    [ExcludeFromCodeCoverage]
    internal sealed class NotNullIfNotNullAttribute : Attribute
    {
        /// <summary>
        /// Initializes the attribute with the associated parameter name.
        /// </summary>
        /// <param name="parameterName">The associated parameter name. The output will be non-null if the argument to the parameter specified is non-null.</param>
        public NotNullIfNotNullAttribute(string parameterName)
        {
            ParameterName = parameterName;
        }

        /// <summary>
        /// Gets the associated parameter name.
        /// </summary>
        public string ParameterName { get; }
    }
    
    /// <summary>
    /// Specifies that when a method returns <see cref="ReturnValue"/>, the parameter will not be null even if the corresponding type allows it.
    /// </summary>
    [AttributeUsage(AttributeTargets.Parameter, Inherited = false)]
    [ExcludeFromCodeCoverage]
    internal sealed class NotNullWhenAttribute : Attribute
    {
        /// <summary>
        /// Initializes the attribute with the specified return value condition.
        /// </summary>
        /// <param name="returnValue">The return value condition. If the method returns this value, the associated parameter will not be null.</param>
        public NotNullWhenAttribute(bool returnValue)
        {
            ReturnValue = returnValue;
        }

        /// <summary>Gets the return value condition.</summary>
        public bool ReturnValue { get; }
    }
}